I've been told (I could never confirm it) that in the time of video tapes VHS won over the much better Betamax and VCC2000, solely because Betamax and VCC2000 banned porn on their tapes and VHS did not. I don't know if it's true, but knowing humans, I deem it plausible.
Now porn is apparently as old as human civilization in general. Some artwork of very long ago that is clearly meant to be pornographic have already been found. So when games as medium came to be it's not that hard to imagine games like that would be there too.
I must note that I do agree with NLCH about the "right" to porn. Now I don't deem porn itself as a right, but once porn can be banned than basically anything can be banned, and also games in which the developer did a statement that may seem "politically incorrect". And then the same can also be done with books, film, music, drawings, well anything. And yeah, I can see some propaganda against porn, like a video were "Disney heroes were raping each other". It was just a porn video about orgy where everybody was initially dressed as Disney princes and princesses, yes. But we do know rule #34: "There is porn of it! No exceptions!" And I've seen more like that. But then again, the anti-porn thing is nothing new. Sexual activity in general even. The idiotic story that you'd get blind when you masturbate appears to have been an actual campaign set up by the church and loads of people even believed it (and I really cannot find any medical logic how your eyes could be affected in anyway at all by this).
Long story short... Porn has always been a thing for discussion. Quite often it's all pretty bizarre.